Clear Creek / North Clear Creek Overview Highlight Past - - PowerPoint PPT Presentation

Clear Creek / North Clear Creek Overview

Highlight Past

Improvements

Discuss Feasibility Study

& Record of Decision North Clear Creek

Metals of Concern

Zinc, Copper, Manganese

Cadmium, Aluminum, Iron

The Upper Clear Creek Watershed and Superfund Study Area

Clear Creek / Central City Superfund Site

Completed Remediation Efforts

• n Main Stem of Clear Creek

1994 - Present

Mine Waste Pile Cleanups

1998 - Argo Water

Treatment Plant

Argo Tunnel

Downsteam Idaho Springs, Dis-Zn

300 600 900 Autumn Winter Spring Summer

Quarter Streamflow, cfs

150 300 450 600 750

Dis-Zinc Conc., ug/L

Pre Q (cfs) Post Q (cfs) Pre D-Zn Post D-Zn

Downsteam Idaho Springs, Dis-Zn

Autumn Winter Spring Summer

Quarter

150 300 450 600 750

Dis-Zinc Conc., ug/L

Pre D-Zn Post D-Zn

Segment High Flow May 1 Through August 31 Low Flow September 1 through April 30 North Clear Creek Segment 13b 80 184 Clear Creek Segment 11 53 103

Seasonal Hardness

Clear Creek Below Idaho Springs and at Golden Dissolved Zinc

Kermits, Dissoved Zinc

300 600 900 Autumn Winter Spring Summer

Quarter S tream flo w , cfs

200 400 600

D is-Z in c C o n c., u g /L

Pre Q (cfs) Post Q (cfs) Pre D-Zn Post D-Zn

Golden Dissolved Zinc, Pre- vs. Post-4/98

300 600 900 Autumn Winter Spring Summer

Quarter S tre a m flo w , c fs

200 400 600

D is -Z in c C o n c ., u g /L

Summary of Remedial Action Objectives

• North Clear Creek to Improve North Clear Creek
• North Clear Creek is significantly impaired. Improvement of surface water quality to a point that

is protective of aquatic life (i.e., survival of a brown trout population) is a goal of the OU4 remedy.

• North Clear Creek to Improve Clear Creek.
• Do not degrade drinking water supplies obtained from Clear

Creek.

• Reduce the toxicity to aquatic insects by reducing metal in

sediments.

• Control or reduce runoff from tailings/waste rock piles to

reduce sediment loading of streams and ground water.

• Sediment loading from the piles continues to degrade water quality and habitat in receiving

streams, and may continue to limit habitat for aquatic life.

Low Flow High Flow

.

Pile Remedial Action Old Jordan Remove (to Druid) Niagra Remove Mattie May Cap with Rock Baltimore Cap with Rock Centennial Remove Pittsburgh Cap with Rock Upper Nevada Gulch Piles Soil Cap and Revegetate (northern aspect) Upper Nevada Gulch Piles Cap with Rock (southern aspect) Gregory Gulch No. 3 Remove Argo Cap with Rock Druid Soil Cap and Revegetate Iroquois Cap with Rock Anchor Soil Cap and Revegetate Hazeltine Soil Cap and Revegetate

Priority Waste Piles

North Clear Creek Removal Needed Low Flow

Concentration/Mass Flux Zinc (dissolved) Copper (dissolved) Cadmium (dissolved) Manganese (dissolved) Iron (total recoverable) Current Low-Flow Conditions Concentration (μg/L) 1,657 15.5 6.0 3,579 7,856 Low-Flow Goals Concentration (μg/L) 675 15.1 3.5 2,021 5,400 Load Reduction Required to Goals Under Low-Flow Conditions

Percent Reduction 59% 2% 41% 44% 31%

Alternatives Considered

Alternative 1A & B No Action / Institutional Controls Alternative 2A & B

Tier 1 Sediment Reduction (Tributaries and North Clear Creek)

Alternative 3A, B & C Water Treatment at Argo, at New

Plant in NCC, varying Tiers of Sediment Reduction

Alternative 4A & B Passive (Wetland Substrate),

Combined Active and Passive Water Treatment with Tier 2 Sediment

Preferred Alternative (4B)

Treatment of Gregory Incline and Gregory

Gulch ground water at Bates Hunter

Treatment of National Tunnel with a wetland Sediment Controls – Detention ponds & mine

waste capping on Russell & Gregory Gulch

North Clear Creek improvements Cost 11.8 Million, $900,000 / year operations

Low Flow High Flow

Anticipated Load Reduction (NCC) Alternative 4B

Percent Reduction in Loading for the Given Flow Regime

Source Area

Low-Flow High-Flow Gregory Incline 99% 85% National Tunnel 85% 85% Gregory Gulch 25% 45% Russell Gulch 20% 40% Chase Gulch 10% 5% Non-Point Sources 40% 40%

Waste Pile Remedial Action Capped Surface Area (acres) Volume Removed (cy) Length of Channel Stabilization (ft) Old Jordan Remove (to Druid) 2,900 200 Mattie May Rock Cap Baltimore Rock Cap Argo Rock Cap Pittsburgh Rock Cap Druid Soil Cap 19.0 Upper Nevada Gulch (South Aspect) Rock Cap 16.5 4,800 Upper Nevada Gulch (North Aspect) Soil Cap 16.5 Gregory Gulch #3 Remove 3,700 300 Centennial Remove 1,500 100 Niagra Remove 5,600 200 Iroquois Rock Cap 3.0 300 Hazeltine Soil Cap 0.9 300 Anchor Soil Cap 1.9 300 Total 67.8 13,700 9,200 10.0 2,700

Provide Comments on the Proposed Plan

Next Steps

Public Comment 8/23 Agencies consider

comments and prepare a Record of Decision by 9/30/2004